Attack on the uncastled king: queen to a7 (a6)
c9-16887naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Mate in 3: a forced sequence that ends in checkmate.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1860 ShuffleRating — for advanced tacticians.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king b1, queen a6, rook d1 b3, bishop g1 h1, knight e1 f1, pawn b2 d2 e2 h2 g3 a4 f4.
Black: king b8, queen d7, rook d8, bishop g8 h8, knight d6 f8, pawn a5 c6 b7 e7 f7 g7 h7.
15 white and 14 black pieces are on the board; the puzzle position arises after move 9.
The position in numbers
White are ahead by 5 points of material (38 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on b8.
It is White to move on move 9, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: c.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
9. Qa7+ Kc7 10. Bb6+ Kc8 11. Qa8#
Why it works
- Great move! queen to a7 keeps the pressure (#2).
- Spot on — bishop to b6 (#1).
- Strong! queen to a8 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Kc7, then Bb6+ and you stay on top.
Move by move
- 9. Qa7+ — queen to a7 with check
- Kc7 — king to c7
- 10. Bb6+ — bishop to b6 with check
- Kc8 — king to c8
- 11. Qa8# — queen to a8 and it is checkmate
Types in this puzzle
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
Early queen raid
From an odd starting square the queen raids before defences exist.
The early queen raid: from an odd starting square the queen bursts into the game before any defense exists. In classical chess an early queen sortie gets punished, but in Chess960 it sometimes hits squares that literally no one can defend. The sign: within a move or two the queen reaches an unprotected pawn or piece near the enemy king. First check whether the queen can be chased with tempo — otherwise the raid just loses time.
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #911.
SP-911 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on b1, the rooks on a1 and d1, the queen on c1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the RampartGuard family; read right to left it becomes position 48.
The engine's main line opens with a4.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #911Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-911
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